Development and Optimization of Ball Bearing Race Geometry and Ferrofluid Pressure Seals for EVA Space Suits

Abstract

Ball Bearings used by NASA, NPP Zvezda, and private aerospace corporations for space suits have not seen significant change since their inception. Plastic pressure and dust seals and two axis normal contact point designs are historically prolific, al- though four contact point geometries are attracting increasing interest. Problematic larger diameter bearings, such as the ones planned to be included for the shoulder, waist, and hip bearings in the new xEMU and Z-2 space suits, will particularly benefit from race and pressure seal design improvements. Four contact point geometries reduce race wear and friction over time and angled contact points improve performance in axial loading. Ferrofluid pressure seals have immeasurably low leakage, long lifetimes, and extremely low mechanical friction. They are extremely effective for sealing against typical dust particles, and have high potential for sealing against small and ferromagnetic regolith particles. This improvement would eliminate the need for many separate dust sealing systems. This thesis demonstrates the ability of these technologies to be implemented into existing EVA space suit designs while adhering to NASA regulations. This thesis also evaluates the effectiveness of various novel race and pressure seal configurations.